Some food for thought:
This is a beautiful scope, worth far more and almost new.
If the item is stolen, just if, the buyer faces civil charges from the owner and separate criminal charges.
Unlike Craiglists which can be anonymous, eBay leaves an audit trail to control sale of stolen items, they are very good at it now.
Given the scope is worth over $10K, if you get over $5K for it by US law it is no longer considered small claims, were few law enforcers care [ like trying to recover a lost laptop or cell phone.] If its sold on eBay, and the original owner wants it back, the secondary seller is now liable to both the original owner and the person he sold it too.
The degree of the crime depends on what the original owner will value it as. Sale of stolen goods across state lines often elevates a misdemeanor into a felony.
Any burden of proof that the buyer was not an accomplice to a crime rests with the buyer, and whether the law officers will bother to press charges for possession:
http://criminal-law.freeadvice.com/white_collar_crimes/crime_property.htmhttp://definitions.uslegal.com/n/national-stolen-property-act-nspa/Most electronics are not investments, they are expenses.
Investments appreciate over time, make you money.
Expenses depreciate, lose money over time.
If you sell a piece of high end gear that is no longer new, what you are getting is its residual value, its often less than the item bought new, for example if you bought a second hand HP 3458a, new about $10k sold by Agilent, it eBays for about $5k.
Good luck!